The present invention relates to devices and techniques for accurately positioning the sight of a firearm, and more particularly deals with in-bore laser devices and methods of using such devices to improve the positioning accuracy of a firearm's sight.
Use of sights for aiming firearms, such as rifles and pistols, is well known. Ideally, when a firearm's scope is properly adjusted, the projectile shot from the firearm will strike the target at a known position identified through visual alignment with a feature of the scope, such as the intersection of scope cross-hairs. Understandably then, those with skill in the art desire efficient techniques for accurately positioning a firearm's sight.
U.S. Pat. No. 5,787,631 ("'631 patent") issued to Kendall discloses an array of prior techniques for use in aligning firearm sights. For example, the '631 patent discloses a technique in which a series of rounds are shot at a target, each followed by comparison between the anticipated target spot as viewed through the sight and the corresponding actual striking location for the given round. The comparisons were used to refine the position of the firearm sight. Presumably, this "trial and error" approach is time consuming, and wastes ammunition.
The '631 patent also discloses a group of laser-based techniques for aligning a firearm sight, and in particular, focuses on U.S. Pat. No. 5,365,669 ("'669 patent") issued to Rustick et al. The '631 patent identifies a problem with the '699 patent approach, and proposes a solution therefor. Specifically, one of the main problems associated with the '699 patent was that the laser beam emitted from the laser module would likely fail to clear the bore of the rifle, unless suitable laser alignment was provided.
In response, the '631 patent proposed using set screws to facilitate laser module alignment. Specifically, the '631 patent disclosed a housing including a threadedly engaged inner sleeve, which contains a laser module and a battery. Four set screws penetrate the housing to facilitate movement of the laser module, presumably into a properly aligned position. Additionally, the '631 patent discloses the use of a springbased switch mechanism to operate the laser module. Specifically, when the '631 device is inserted into a firearm and the firearm's bolt is engaged, the force of the bolt closes the switch mechanism to activate the laser module.
Though the '631 patent asserts to have overcome certain shortcomings of the prior art, it too has limitations. For example, using four set screws to align the laser module is a cumbersome and time consuming task. Each time the user makes an adjustment, one set screw is tightened, and an opposing set screw must be loosened to permit free motion for the laser module. Moreover, with each adjustment of the laser module, the user has to evaluate its effectiveness in planning the next adjustment. The process is inherently complex, as it involves coordinated adjustments along multiple axes of motion for the laser module.
Another problem affiliated with the '631 patent resides in the switch mechanism. Pressing the switch 8 at that back of the '631 device energizes the laser module. This can be carried out when the device is loaded into a firearm, as desired, due to the force of the firearm's engaged bolt. Similarly, the laser module can be activated when the '631 device is out of the firearm, as pressing switch 8 energizes the laser module regardless of whether the device is or is not located within the firearm. Thus, a user can prematurely drain the device's battery by inadvertently closing switch 8 by, for example, putting the device in a coat pocket. Switch 8 poses yet another problem, namely, that it incorporates movable components subject to eventual inoperability due to normal wear and tear.
There therefore was a need for an improved laser device for use in adjusting a firearm's sight, and a method for aligning a laser module that overcome the limitations of prior devices and techniques.